ISPs are not delivering the transmission rate either. They are over-provisioning, unless you have some special business grade contract. That is why the bandwidth limits (FUPs) exist in the first place.

Furthermore, unless the server you are downloading from is the bottleneck, all the inaccuracies exist in transmission rate as well. It’s the same information, but translated to comprehensible units.

You are making convincing sounding excuses, but they are excuses. Completely divorced from reality.